剑指offer-两个链表的第一个公共节点

 1 /*
 2 struct ListNode {
 3     int val;
 4     struct ListNode *next;
 5     ListNode(int x) :
 6             val(x), next(NULL) {
 7     }
 8 };*/
 9 class Solution {
10 public:
11     ListNode* FindFirstCommonNode( ListNode* pHead1, ListNode* pHead2) {
12         int l1 = GetListLenth(pHead1);
13         int l2 = GetListLenth(pHead2);
14         if(l1 >= l2){
15             int ls = l1-l2;
16             while(ls-- > 0)
17                 pHead1 = pHead1->next;
18         }
19         else{
20             int ls = l2-l1;
21             while(ls-- > 0)
22                 pHead2 = pHead2->next;
23         }
24         while(pHead1 != NULL){
25             if(pHead1->val == pHead2->val)
26                 return pHead1;
27             else{
28                 pHead1 = pHead1->next;
29                 pHead2 = pHead2->next;
30             }
31         }
32         return pHead1;
33     }
34     int GetListLenth(ListNode* pHead){
35         ListNode* p = pHead;
36         int l = 0;
37         while(p != NULL){
38             l++;
39             p = p->next;
40         }
41         return l;
42     }
43 };